This invention relates to apparatus adapted for blending liquids in a gaseous spray stream, more particularly, to such apparatus which functions to aspirate liquids into a gas jet externally of the apparatus for spraying an object with the resulting spray mixture.
Spraying apparatus in which liquids are supplied internally to a gaseous stream for spraying an object with the resulting mixture have long been provided. Internal supply of liquids to a gaseous stream with the liquids internally blended in the stream has certain disadvantages. Among others, the internal spaces containing liquids may present a cleaning problem, such as when it is desired to change the liquids in the apparatus. The problem may be more acute employing reactive liquids, for example, two-component epoxy paints. Relatively complex and precise blending apparatus is required in order to provide for variations in mixing ratios of the liquids.
Numerous sprayers have been provided that operate by external aspiration of a fluid utilizing the suction effect of a gas jet. It appears that the sprayers of this type have aspirated but a single stream of liquid, although it was known to blend two liquids prior to aspiration into the stream to be aspirated. It has also been known to externally produce a spray mixture by supplying pressurized liquids to a gas jet.